Michael,
Do not make any rash decisions! My shrink always told me "When in stress, make only one major decision at a time. And make no radical life changes." You are in acute stress. Now is not the time to decide about your business. Most of the what-ifs won't happen. You'll have to make some changes and modifications but, most likely, you'll be able to keep your business. Family and friends will help if you let them.
And even though you look swollen and odd after the neck resection, you'll go back to almost normal. Honestly. No one can tell I had mine and because they took all the nodes out of my neck and tightened up that skin, I actually look much younger than my age. I'll email you a picture.
It's completely understandable why this would freak you so. Your past experience with your dying partner. That was a terrible experience. Please consider some therapy time to help get perspective. The hospitals and county often have great programs. It saved my sanity and got me out of panic-mode.
I did surgery first, rad after, and apparently am still free in the primary site 12 years later. But mine was more advanced when they found it so they had to be aggressive. Take deep breaths, stare at the ocean and let your inner calmness take over. And make no radical changes to your lifestyle! Yet. Ali Mae